Walther introduced their original PP ("Polizei Pistole") compact semi-automatic pistol in 1929 and immediately found takers beyond the originally intended police market. 1931 saw the introduction of an even more compact form in the PPK which ended up becoming the more popular and famous of the two - beyond its service it World War 2 (1939-1945), it found use as Adolph Hitler's suicide weapon and as the sidearm of fictional British super-spy "James Bond". The PPK introduced a more compact design intended for concealed carry while retaining much of the key usability and safety qualities of the original, successful PP design. Millions of PP/PPK pistols have been produced since their introduction, manufacture of the types still continuing even today (2013). The "PPK" initials stand for "Polizei Pistole Kriminalmodell".
The base PPK design was chambered for the same 7.65mm cartridge as the original PP though now fed through a 7-round detachable box magazine as opposed to the original's 8-round count. It sported a length of 5.8 inches (compared to 6.4 inches in the PP) with a 3.15 inch barrel assembly. The PPK retained the same straight forward blowback system of operation as the PP, the exposed hammer at the rear of the receiver and a double-action trigger function. Its safety features carried over from the PP allowed the operator to carry the gun loaded and ready-to-fire through a long, deliberate trigger pull. Also, the signal pin at the rear of the receiver (above the hammer) allowed the operator to visibly identify a chambered cartridge (removed on wartime production models for expediency). A plastic magazine extension could be fitted at the base of the grip for a broader landing area for the primary hand's palm and fingers.
Externally, the two pistols were nearly identical save for dimensions and the form of the frame, particularly at the butt. The PP utilized a forged, formed frame with two plastic side pieces making up the grip. In the PPK, the frame was simpler in construction and required a single-piece, wrap-around grip part.
As with the PP, the PPK was developed beyond its standard, original 7.65x17mm Browning SR (.32 ACP) chambering to include support for the 9x17mm Short (.380 ACP), .22 Long Rifle and 6.35x15mm Browning SR (.25 ACP) cartridges.